package ah.filter;
import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;

public class CharsetAllEncodingFilter implements Filter {

private String encoding = null;

/**
* Request.java 对 HttpServletRequestWrapper 进行扩充, 不影响原来的功能并能提供所有的
* HttpServletRequest 接口中的功能. 它可以统一的对 Tomcat 默认设置下的中文问题进行解决而只需要用新的 Request
* 对象替换页面中的 request 对象即可.
*/

class Request extends HttpServletRequestWrapper {
  
   private String encoding = null;

   public Request(HttpServletRequest request) {
    super(request);
    encoding = CharsetAllEncodingFilter.this.encoding;
   }

   /**
   * 转换由表单读取的数据的内码. 从 ISO 字符转到 在web.xml中设置的encoding.
   */
   public String toChi(String input) {
    if(input == null) {
     return null;
    } else {
     try {
      byte[] bytes = input.getBytes("ISO8859-1");
      return new String(bytes, encoding);
     } catch (Exception ex) {

     }
     return null;
    }      
   }

   /**
   * Return the HttpServletRequest holded by this object.
   */
   private HttpServletRequest getHttpServletRequest() {
    return (HttpServletRequest) super.getRequest();
   }

   /**
   * 读取参数 -- 修正了中文问题.
   */
   public String getParameter(String name) {
    return toChi(getHttpServletRequest().getParameter(name));
   }

   /**
   * 读取参数列表 - 修正了中文问题.
   */
   public String[] getParameterValues(String name) {
    String values[] = getHttpServletRequest().getParameterValues(name);
    if (values != null) {
     for (int i = 0; i < values.length; i++) {
      values[i] = toChi(values[i]);
     }
    }
    return values;
   }
}

public void destroy() {

}

public void doFilter(ServletRequest request, ServletResponse response,
    FilterChain chain) throws IOException, ServletException {
   HttpServletRequest httpreq = (HttpServletRequest) request;
   if (httpreq.getMethod().equals("POST")) {
    request.setCharacterEncoding(encoding);
   } else {
    request = new Request(httpreq);
   }

   chain.doFilter(request, response);
}

public void init(FilterConfig filterConfig) throws ServletException {
   encoding = filterConfig.getInitParameter("encoding");
}

}